The present disclosure relates to the subject matter contained in Japanese Patent Application No.2002-124572 filed on Apr. 25, 2002, which is incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to a fuel cut-off apparatus disposed on a passage for communicating the inside of a fuel tank with the outside thereof, and shutting off the passage when the liquid level of fuel rises within the fuel tank, for example, during the refilling.
2. Description of the Related Art
A fuel tank for the vehicle is provided with a fuel cut-off apparatus, which allows the gas in the fuel tank to escape to the outside thereof during the refilling so that it becomes possible to refill, and automatically shuts off the passage to tightly close the fuel tank and to stop the refilling when the fuel is filled up to rise the liquid level. Also, the fuel cut-off apparatus is provided on a passage for passing the fuel evaporated within the fuel tank into a canister.
U.S. Pat. No. 4,982,757 (corresponding to JP-A-2-112658) and U.S. Pat. No. 5,832,950 (corresponding to JP-A-9-79405) disclose such fuel cut-off apparatus. However, with the fuel cut-off apparatus according to the related publications, when the liquid level of fuel falls, the buoyancy of float is not exerted so that a valve thereof is opened by the own weight of the float. Therefore, it is not possible to resolve sticking of valves unless the volume of float is increased, resulting in a problem that the fuel shut-off apparatus can not be made compact.
Also, with the fuel cut-off apparatus according to the related publications, when the liquid level of fuel reaches a predetermined height during the refilling, all the valves are cut off, and the tank is fully closed at this time, resulting in a problem that additional refilling is not allowed after automatic stop of a feed oil gun.
It is an object of the present invention to provide a fuel cut-off apparatus for fuel tank, which securely prevents sticking of valves when the liquid level of fuel falls and allows for additional refilling after automatic stop of the feed oil gun.
In order to accomplish the above object, according to a first aspect of the invention, a fuel cut-off apparatus for a fuel tank, is disposed in a passage for communicating inside of the fuel tank to outside thereof and shutting off the passage when the liquid level of fuel within the fuel tank rises. The fuel cut-off apparatus includes a case, a first seal seat, a first float valve body, a second seal seat, a second valve body, and a second float. The case is attached to a wall portion of the fuel tank and having a first passage and a second passage for communicating the inside of the fuel tank to the outside thereof. The first seal seat is disposed in the first passage of the case. The first float valve body is disposed in the case and closes the first seal seat in response to the liquid level of the fuel when the liquid level rises. The second seal seat is disposed vertically above the first seal seat, in the second passage of the case. The second valve body is disposed on one side of the second seal seat communicating to the outside of the second passage, and is resiliently urged upwards from below. The second float is disposed in the case and regulates an upper end position of the second valve body to open the second valve seat in response to movement of the liquid level of fuel at least until the liquid level is higher than the liquid level at which the first float valve body closes the first seal seat. The second valve body closes the second seal seat when the second float does not regulate the upper end position of the second valve body.
With the first aspect, if the liquid level of fuel within the fuel tank reaches a certain height, the first float valve body makes contact with the first seal seat to close the first passage, so that the internal pressure of the fuel tank is increased to automatically stop a feed oil gun. However, at this time, the second valve body is still opened with an upper end position regulated by the second float, so that there remains a narrow passage for allowing the gas within the fuel tank to escape to the outside. As a result, the additional oiling is enabled by operating the feed oil gun. If the liquid level of fuel further rises, the second float rises and the second valve body closes the second seal seat, so that the fuel tank is fully closed to disable the additional oiling and the refueling is completed.
Then, if the liquid level of fuel falls, the second float firstly falls to press down the upper end of the second valve body and open the second seal seat. At this time, when the internal pressure of the fuel tank is high, the conventional device has a force exerted in a direction for closing the valve. However, in the first aspect, the internal pressure of the fuel tank is exerted in a direction for opening the second valve body, because the second valve body is disposed on the side of the second seal seat communicating to the outside of the second passage. As a result, the second valve body is rapidly opened without sticking to the second valve body. If the liquid level of fuel further falls, the first valve body is opened this time, so that the first passage communicates to the outside. At this time, the second valve body is already opened, so that the internal pressure of the fuel tank and the outside pressure are in equilibrium, whereby the first valve body does not stick to the first valve seat.
According to a second aspect of the invention, in the first aspect, the second passage is connected to the first passage at a position vertically below the second seal seat.
With the second aspect, even if the fuel enters the second passage in a state where the second valve body closes the second seal seat, and accumulates over the second seal seat closed by the second valve body, the fuel flows through the second seal seat downwards to enter a first communication passage to return to the fuel tank, when the second valve body is opened. As a result, the accumulated fuel is surely prevented from being derived to the outside.
According to a third aspect of the invention, in the first or second aspects, the second float includes a second float main body rising as the liquid level of the fuel rises, an overhang portion extending upright from the second float main body and overhanging above the second valve body, and a second valve body pressing portion extending from the overhang portion to be close to the second float main body and abutting against the second valve body to press down the second valve body.
With the third aspect, the second valve body resiliently urged upwards from below toward the second seal seat is pressed down by the second valve body pressing portion of the second float main body, when the liquid level of fuel within the fuel tank is low. The second valve body pressing portion has no regulation to cause the second valve body to contact with the second seal seat due to its resilient urging force, and close the second passage, when the liquid level of fuel within the fuel tank rises to cause the second float to rise.
According to a fourth aspect of the invention, in the third aspect, the case includes a cylindrical case main body receiving the first float valve body and the second float main body, and forming the first passage, and an upper body assembled on an upper portion of the case main body to derive the first passage to the outside thereof and forming the second passage between the upper body and the case main body. The overhang portion extends into the second passage through an opening defined at an upper wall of the case main body.
With the fourth aspect, since the second passage is formed between the case main body and the upper body, and the overhang portion is introduced into the second passage side, the second valve body disposed on the side of the second seal seat communicating to the outside of the second passage and resiliently urged upwards from below is pressed down by the second valve body pressing portion.
According to a fifth aspect of the invention, in the third or fourth aspects, the valve body pressing portion of the second float has a plurality of ribs projecting from an axial center in outer diameter directions to form a vent path between the ribs. Lower end faces of the ribs have concave shapes to position the second valve body. At least one of opposed faces of the second float main body and the first float is partially formed a convex portion for preventing the intimate contact of the first float and the second float main body.
With the fifth aspect, since the valve body pressing portion has the plurality of ribs projection from the axial center in the outer diameter direction to form the vent path between the ribs, the second passage is not closed by the valve body pressing portion. Also, since the lower end face of the valve body pressing portion is concave to position the second valve body, the second valve body is always contacted with the second seal seat at proper position without preventing the second valve body from being eccentric. Moreover, since either one of the opposed faces between the second float main body and the first float is partially formed with the convex portion for preventing the intimate contact of both, it is possible to prevent the second float main body and the first float from being contacted and moved together to disable the up and down operation to be made independently.
According to a sixth aspect of the invention, in any one of the first to fifth aspects, the first seal seat is formed on a partition wall disposed in the case main body. The second valve body and a resilient urging member for urging the second valve body upward from below are sandwiched between the partition wall and an inner wall of the case main body to define the second passage.
With the sixth aspect, since the partition wall is provided, the first seal seat is formed and the second passage is demarcated, whereby the second valve body and its urging means are easily installed.
According to a seventh aspect of the invention, in any one of the first to sixth aspects, the first float valve body includes a first float main body, a cap portion assembled via a gap on an upper portion of the first float main body, and a first valve body fitted to an opening portion defined in the cap portion.
With the seventh aspect, since the first float valve body includes the first float main body and the cap portion, the cap portion is provided with an opening portion for fitting the first valve body to occupy as large a volume of the first float valve body as possible. Also, since the first valve body is fitted into the opening portion of the cap portion, it is possible to prevent the first valve body from being out of place, even if the first valve body made of rubber is swollen by the fuel.
According to an eighth aspect of the invention, in the seventh aspect, the gap between the first float main body and the cap portion of the first float valve body communicates to a space defined in the case main body.
With the eighth aspect, even if the fuel enters into the gap between the first float main body and the cap portion, the fuel is rapidly flowed back into the space within the case main body, and then into the fuel tank, whereby it is possible to prevent the fuel from remaining in the gap and flowing outside.
According to a ninth aspect of the invention, in any one of the first to eighth aspects, the case main body has one internal space having one of approximately columnar shape and approximately prismatic shape. The first float valve body and the second float complement each other to have a shape adaptable to the one internal space.
According to the ninth aspect, the entire device is made compact while the volume of the first float valve body and the second float is made as large as possible.
According to a tenth aspect of the invention, in the ninth aspect, the overhang portion of the second float has a plurality of leg portions. The leg portions are inserted through a plurality of corresponding openings defined on an upper wall of the case main body into the case main body and connected to the second float main body.
With the tenth aspect, since the overhang portion of the second float has the plurality of leg portions, which are inserted through the plurality of openings provided on the upper wall of the case main body and linked to the second float main body, the up and down operation of the second float is guided by the leg portions inserted into the opening to be regulated in rotation. Consequently, the first float valve body having a shape complementary with the second float within the case main body is also regulated in rotation, and thereby correctly contacted with the first seal seat without providing any guide for the first float valve body.